Light signal for railroads



O. s. Fil-:LD 2,lZ5,257

LIGHT SIGNAL FOR RAILROADS Juy 26, 1938.

Filed Feb. 2l, 1935 2 Sheets-Shea?l 1 Flai.

INVENTOR BY E 32 i ATTORNY I July 26, 1938 o. s. FIELD LIGHT SIGNAL FOR RAILROADS Filed Feb. 21, 1935 2 sheets-sheet 2 Fla@ INVENTOR BY @5 Wd Patented July 2 6, 1938Vv PATENT OFFICE LIGHT SIGNAL FOR RAILROADS Oscar S. Field, Rochester, N. Y., assigner to General Railway Signal Company, Rochester, N. Y.

Application February 21, 1935, SerialNo. 7,565

Claims.

This invention relates to color light signals for railroads, and more particularly to improvements in the motor devices for such a signal of the socalled search light type which employs a movable color screen.

In one type of color light signal commonly used on railroads, such as disclosed in my prior Patent No. 1,835,150, December 8, 1931, a threeposition motor device is employed to move a spectacle or color screen to any one of three different positions so as to display the desired color indication. It is desirable that such a motor device should be efficient and yet provide substantial operating forces with relatively small currents to actuate contacts and overcome biasing counterweights; and at the same time this motor device should have such size and rigidity of parts, large clearances and the like, as to be highly reliable in its operation, and particularly free of the possibility of sticking by any derangement of parts or the eifect of continued use. Among other things, it has been found expedient to mount the shaft of such a three-position motor device or knife-edge bearings to have a minimum amount of friction and tendency to stick in use. likewise, it is desirable to have a relatively high ratio of the drop-away current to the normal operating current.

With these and other considerations in mind, it is proposed in accordance with this invention to improve the eld and armature structure of such a motor device, more particularly of the type disclosed in my prior patent above mentioned, and also my prior application, Ser. No. 470,056, filed July 23, 1930, now Patent No. 2,097,785 dated November 2, 1937 so that the forces reacting upon the shaft upon the application of turning torque will tend to maintain the shaft at both ends in contact with the knifeedge bearings, and further so that an increased torque by direct magnetic attraction will be effective near the extremes of the movement of the shaft where a greater operating force is desirable to provide adequate Contact pressure.

Various other characteristic features, attributes and advantages of the invention will be in part apparent and in part explained as the description progresses.

In the accompanying drawings, Fig. l shows generally the organization of a color light signal embodying my improvements, this figure showing a vertical longitudinal section through the motor device; Fig. 2 is a transverse section through the motor device substantially on the line 2 2 of Fig. 1; Fig. 3 is a diagrammatic perspective of the more essential parts of the field and armature structure; Fig. 4 is a fragmentary edge view of one of the pole pieces; and Fig. 5 is an explanatory diagrammatic view of counterweight and contact operating mechanism.

Considering rst the general organization of the type of signal with which my improved motor deviceV is used, the preferred construction is illustrated and described in my prior Patent No. 1,835,150, and also in my prior application above mentioned; and this preferred organization in general comprises a lamp I 'with a concentrated filament, a reflector 2, and a sector shape spectacle frame or color screen 3 disposed near the focal point of the reflector and movable to interpose green, yellow, or red color glasses in the light beam',y projected through the lens 4 at the front of the signal. The primary purpose of the motor device of this invention is to move the spectacle or color screen 3 from an intermediate position to which it is biased by suitable counter- Weights, to either of two extreme positions, and also to actuate contacts in such extreme positions.

The motor device comprises a shaft 5 of suitable magnetic steel with axial bores in the ends in which are pressed and secured spindles B of hardened steel. The end portions of the armature shaft 5 are shouldered and threaded; and two armature Wings or vanes 'l and 8 of a general sector shape, as best shown in Fig. 3, are clamped to the ends of the shaft by nuts 9 on said threaded portions. The armature vanes l and 8 extend radially froml the shaft 5 in opposite directions, the vane 1 in the front as viewed in Fig. 3 extending downward, and the other vane 8 in the rear extending upward. The color screen 3, with the three colored glasses or mountings G, Y, or R therein, is fastened to the armature vane 8 (see Fig. 2). The armature shaft is supported on knife-edge bearings; and in the preferred construction, the spindles 6 are formed with recesses and supported on hardened knife edges I0, together with a ball thrust bearing, in the manner disclosed more in detail in the patent to J. L. Osborne, No. 1,785,702, December 16, 1930.

In the preferred construction, the armature shaft 5 is surrounded by a copper sleeve l2 attached thereto; and around this sleeve with a relatively large clearance, is another copper sleeve I3 on which is wound the armature coil or winding lil. This armature coil is surrounded by a split sleeve cover I5, preferably of suitably insulated material, which is supported by the main frame of the signal.

The armature shaft 5 and vanes l and 8 are biased to an intermediate position shown in Fig. 3 by two counterweights I6 pivoted at Il as shown in Fig. 5.

A counter-balancing member I8 in the form of a casting of substantially the same contour as that of the armature vane 1 is secured thereto by rivets or the like; and the distribution of weight in this member I8 is varied by borings in accordance with common practice so as to counterbalance accurately the color screen or spectacle 3. At the upper edge of this member I8 is a curved flange I9, to which two links 20 are pivotally connected at their upper ends; and the lower ends of these links are slotted and engage with pins 2i xed in the two counterweights I8. A block of suitable insulating material is xed to the end of each counterweight I6; and

to this block is fixed a spring contact member 22 so arrangedV as to engage stationary contacts 23 in the two extreme positions of the counterweight, with the appropriate contact pressure. It will be evident that when the armature shaft 5 is turned in one direction, say clock-wise as viewed in Fig. 5, the left-hand counterweight i6 is raised by the link 26 and the left-hand contact nger 22 is shifted. Suitable adjustable stop screws 2li and 25 limit the upward and downward movement of each counterweight I6.

The field structure of the motor device comprises two plates 21 and 28 of magnetic material of a general U-shape with their side portions shaped as shown in Fig. 3 to form curved pole pieces 2171 and 281. These plates 2 and 28 are supported in the signals by bolts 29 (the ends of which appear in Fig. 1), passing through holes 30 in said pole pieces. The two U-shaped field core members 2 and 28 are connected at the bottom by four permanent bar magnets 3i, arranged in pairs with spacers supported by clips 32 and clamped by a through bolt 33.

So far described, the structure and assembly of the motor device is substantially the same as in my prior patent; but in the improved arrangement the front armature vane 1, as viewed in Fig. 3, is disposed in front of the curved pole pieces 271-281; and the other rear armature vane 8 likewise is disposed on the same side or in front of the other pole pieces 271-281. Also, the rear pole pieces Eil-231 are preferably slotted to form strips or lips 35, which are bent forward to provide edges constituting pole pieces in the path of movement of the vane, as shown in Figs. 3 and 4.

The permanent magnets 3l make the front and rear pole pieces 281-281 at the right-hand side of the armature shaft 5, as viewed in Fig. 3, of one magnetic polarity say north as indicated by N; and the other two pole pieces at 2'i1-2i1 at the left of the shaft 5 are of the opposite magnetic polarity S. When current flows through the armature coil M in one direction and makes the front armature vane l a south magnetic pole, and the rear armature vane 8 a north magnetic pole, as indicated N and S, the front downwardly extending armature vane 'i is moved to the right by the repulsion and attraction with the cooperating pole pieces; .and the rear armature Vane 8 is similarly moved to the left.

Referring more particularly to Fig. 3, it can lbe seen that the forces of magnetic attraction between each of the rarmature varies 'i and 8 and their co-operating pole pieces 2l and 28 act in the same direction longitudinally of the shaft and tend to move it lengthwise in one direction (to the rear as viewed in Fig. 3) against the ball thrust bearing at the end of the shaft. 'Ihese armature vanes l and 8, however, are disposed to extend radially from the shaft 5 in opposite directions, in order that the weights of these vanes may counter-balance each other; and the components of the forces of magnetic attraction which act on these vanes and which tend to move or tilt the armature shaft 5 transversely of its axis, are opposed to each other. For example, such component acting on the front Vane l as viewed in Fig. 3 and indicated by the arrow a tends to pull down the front end of the shaft 5 against its knife-edge bearing, and the similar component acting on the rear armature vane 8 and indicated by the arrow b tends to push down the rear end of the shaft against its bearing.

In other words, in accordance with the improved arrangement constituting this invention, the armature vanes 'I and 8 are disposed so that the forces of attraction acting thereon and exerting a tendency to tilt the armature shaft 5 transversely of its axis are in opposition, rather than cumulative as in my prior Patent No. 1,835,150, with the result that the tendency to lift the armature shaft oif of its knife-edge bearing at either end is greatly reduced, if not entirely eliminated.

. In this connection, it is evident that variations in the air-gap between the armature vanes and their co-operating pole pieces, together with changes in the flux distribution and the relative dimensions of the parts, will affect the relative intensity and direction of the forces of magnetic attraction acting on the armature vanes, so that in structures manufactured on a commercial basis the components tending to tilt the armature shaft may not be exactly balanced and there may be a downward pressure on the bearing at one end of the shaft or the other greater than the weight of the armature element; but even with such variations incident to commercial manufacture, it is found that these components are so nearly balanced that the armature shaft will not be actually lifted off of its knife-edge bearing at either end.

This relative disposition of the armature vanes l and 8 and their co-operating pole pieces 27 and 28 constitutes an important feature of this invention, because it avoids lifting of the bearing spindles 6 of the armature shaft 5 off of the knife-edge bearings, and thus obviates the possibility of undesirable frictional engagement between the end of a spindle and the cap or retaining member of its bearing. Since the attractive forces acting onboth the armature varies 'i and 8 tend to hold the armature shaft on its knife-edge'bearings, more positive and accurate -alinement of the shaft is obtained, thereby assuring less chance of rubbing contact between the armature vanes and the pole pieces or other parts with desired air-gaps or clearances.

During the latter part of the movement of the armature shaft 5 from its intermediate position in either direction, the corresponding VContact finger 22 engages its normally open stationary contact 23,' and a greater operating torque at this point of movement is desirable to assume the increased load of exerting the desired contact pressure. Such increase in torque on the armature shaft 5 is obtained in accordance with this invention by the projecting ledge or lip 35 which, as shown in Figs. 3 and 4, is disposed in the path of movement of the rear armature vane 8 so that, as this vane approaches the position-where the contact load is applied, there is a direct magnetic attraction between the edge of this armature vane and the pole face provided by said projecting lip 35, said force of magnetic attraction producing an increased torque on the armature shaft by acting through the lever arm represented approximately by the radius of the armature vane. It is found that such a lip 35 materially increases the torque on the armature shaft 5 at approximately the point in its movement where 75 such additional torque is desired to exert the required contact pressure. Also, such building up of torque near the extreme movement of the armature shaft improves the drop-away characteristics of the device, and allows relatively large biasing forces in the counterweights I6 and in the contact spring tension to be employed with the desired small operating currents, and with substantial working air gaps.

While the structural features characterizing this invention have been illustrated in connection with one specific type of motor device, as illustrative of the nature of the invention, it should be understood that various adaptations and modifications may be made in the particular construction and arrangement of parts shown and described without departing from the invention.

What I claim is:-

1. A three-position motor device of the character described for operating a movable element from an intermediate biased position in either direction comprising, a horizontally disposed armature shaft supported on knife-edge bearings at its ends, fiat armature vanes of a general sector shape fixed to said shaft between said bearings and extending in opposite directions radially from said shaft in parallel planes at right angles to the axis of said shaft, a stationary field structure having two pairs of fiat pole pieces disposed in planes parallel with said armature vanes and co-operating therewith through a uniform air gap during movement of said vanes, said pole pieces of each pair being disposed on opposite sides of said armature shaft, means for magnetizing the pole pieces of each pair with opposite magnetic polarities, a stationary coil around said armature shaft and adapted when energized to magnetize said vanes with opposite polarities to co-operate with their respective pairs of pole pieces and produce a turning torque for said shaft, said vanes being located on the same side with respect to said pairs of pole pieces so that the forces of magnetic attraction acting on said vanes longitudinally of the shaft are in the same direction, and a ball thrust bearing limiting endwise movement of said shaft, the relative disposition of said armature vanes and their cooperating pairs of pole pieces causing the turning moments of said longitudinally acting forces of magnetic attraction acting on said vanes in directions and at locations tending to tilt said shaft transversely of its axis to be in opposition and thereby avoid lifting of said shaft off of its bearing at either end.

2. A three position motor device of the character described for operating a movable element from an intermediate biased position in either direction comprising, a horizontally disposed armature shaft, knife-edge bearings supporting said shaft at its ends, each bearing including a ball engaging the end of the shaft and limiting endwise movement thereof, flat armature vanes of a general sector shape xed to said shaft between said bearings and extending radially in opposite directions from said shaft in parallel planes at right angles to the axis of said shaft, a stationary coil around said shaft for magnetizing said armature vanes with opposite magnetic polarities, a field structure including two plates of app-roximately U-shape with their end portions constituting pairs of flat pole pieces disposed in planes parallel with said armature vanes and co-operating therewith to produce a turning torque on said shaft, means for magnetizing said plates of the eld structure with opposite magnetic polarities, said armature vanes being located on the same side with respect to said pole pieces so that the turning moments of the components of the forces of magnetic attraction acting on said vanes longitudinally of the shaft in directions and at locations tending to tilt said shaft transversely of its axis are in opposition, thereby eliminating the tendency for said shaft to lift off of its knife-edge bearing at either end.

3. A three-position motor device for operating a movable element from an intermediate biased position in either direction comprising, an armature shaft having flat vanes of a general sector shape extending radially from the shaft in parallel planesl at right. angles to the axis of said shaft, and a field structure having fiat pole pieces disposed in pairs in planes parallel with said vanes, the pole pieces of each pair being located on opposite sides of said armature shaft and co-operating with a corresponding one of said vanes to produce a turning torque for said shaft in one direction or the other through a substantially uniform air-gap, each pole piece of a pair having a portion projecting therefrom in a direction lengthwise of said shaft into the path of movement of the correspon-ding vane to produce magnetic attraction with a corresponding edge of said vane near the extreme positions of said shaft.

4. A three-position motor device for operating movable elements from an intermediate biased position in either direction to extreme positions comprising, an armature shaft having fiat vanes of a general sector shape radially projecting therefrom in parallel planes at right angles to the axis of said shaft, a field structure. including two plates of approximate U-shape with end portions forming fiat pole pieces disposed in planes parallel with said vanes, two of said pole pieces having lips integral therewith and projecting into the path of movement of one of said vanes to co-operate magnetically with the corresponding edges of that vane nea-r the extreme positions of said shaft, adjustable stop means for limiting movement of said shaft at its extreme positions, means for magnetizing said pole pieces, and a stationary armature coil around said shaft for magnetizing said vanes.

5. A three-position motor device for operating the movable elements of color-light signals or the like comprising, an armature shaft, a stationary coil around said shaft, flat vanes fixed to said shaft and projecting radially therefrom in parallel planes at right angles to the axis of said shaft, a eld structure including pairs of flat pole pieces disposed in planes parallel with said va'nes, the pole pieces of each pair being located on opposite sides of said shaft, means for magnetizing said pole pieces of each pair with opposite magnetic polarity, biasing means tending to maintain said shaft and vanes in an intermediate position, and adjustable stops for limiting movement of said armature shaft and vanes at its extreme positions, the po-le pieces of a pair having portions projecting into the path of movement of the corresponding vane and magnetically co-operating with the corresponding edges thereof near the extreme positions of said shaft, thereby increasing the torque on said shaft at approximately the point in its movement where the load of operating said contact means is applied.

OSCAR S. FIELD. 

